Conference services exist in multiple topologies. Different topologies, that is, different networks, may be called a heterogeneous network to each other, such as a local area network inside an enterprise, and a telephony network on the side of an operator. Generally, an enterprise constructs a conference system in an Internet Protocol (IP) network environment of the enterprise. IP terminals of the enterprise, for example, personal computer (PC) terminals, may directly access a conference platform in an IP network of the enterprise. A conference system constructed by an operator, however, may provide conference services toward all network forms, allowing access of terminals in a circuit switched domain, such as mobile phones and fixed-line phones.
The demands for access to the conference system of the enterprise still exist, when an employee of the enterprise is out of the enterprise, for example, on a business trip. Usually, the employee of the enterprise accesses the conference system of the enterprise by means of a mobile phone, a fixed-line phone, and the like. Using this means requires that the enterprise lease a private line from the operator, so as to support access of terminals (mobile phones and fixed-line phones). When the enterprise initiates an outgoing call to the mobile phone or the fixed-line phone of the employee by leasing a private line from the operator, the conference system of the enterprise directly initiates a call to the mobile phone or the fixed-line phone of the employee, the call from the conference system of the enterprise to the mobile phone is routed to a circuit switched domain network of the operator by using the private line, and then the circuit switched domain network calls the mobile phone. When the employee actively attends a conference by using the mobile phone, the operator needs to configure a number for the private line of the enterprise. When the mobile phone calls the conference system of the enterprise, the circuit switched domain network routes the call of the mobile phone to the conference system by using the private line leased by the enterprise.
In the conventional art, however, access of each terminal requires a private line channel, resulting in high cost for maintaining private lines between the enterprise and the operator, thereby unfavorable to popularization. Furthermore, resources of private lines are wasted because diversified types of terminals require that a private line provides a function of routing to the networks of all operators.